A Parametric Stereo (PS) technology may be used to encode a stereo signal. A PS technology may generate a mono signal by down-mixing an inputted stereo signal, extract a stereo parameter indicating side information of the stereo signal, and encode the generated mono signal and the extracted stereo parameter to encode the stereo signal.
In this instance, the stereo parameter may include an Inter-channel Intensity Difference (IID) or a Channel Level Difference (CLD), an Inter-Channel Coherence or Inter-Channel Correlation (ICC), an Inter-channel Phase Difference (IPD), an Overall Phase Difference (OPD), and the like. The IID or the CLD may indicate an intensity difference depending on an energy level of at least two channel signals included in a stereo signal. The ICC may indicate a correlation between at least two channel signals depending on coherence of waveforms of the at least two channel signals included in a stereo signal. The IPD may indicate a phase difference between at least two channel signals included in a stereo signal. The OPD may indicate how a phase difference between at least two channel signals, included in a stereo signal, is distributed between two channels based on a mono signal.